Brushless motor with water stopping walls creating labyrinth structure

Abstract

There is provided a brushless motor including (1) a motor shaft, (2) an insulator that includes a ring-shaped insulating portion covering the ring-shaped unit, (3) a centerpiece that includes a main body section that supports the motor shaft, (4) a first water stopping wall that is formed in a ring shape along the circumferential direction of the motor shaft, and that extends along the axial direction of the motor shaft from the ring-shaped insulating portion toward the main body section, and (5) a second water stopping wall that is formed in a ring shape along the circumferential direction of the motor shaft, that extends out along the axial direction of the motor shaft from the main body section toward the ring-shaped insulating portion, and that, together with the first water stopping wall, configures a labyrinth structure.

What is claimed is: 
     
       1. A brushless motor comprising:
 a motor shaft; 
 a rotor housing including a circular cylinder-shaped shaft bearing housing section provided at the radial direction outside of the motor shaft, and an outer cylinder section formed at the radial direction outside of the shaft bearing housing section; 
 a shaft bearing that is housed in the shaft bearing housing section, and that is assembled to the motor shaft; 
 a stator core that includes a ring-shaped unit provided at the radial direction outside of the shaft bearing housing section, and a plurality of teeth formed in a radiating pattern at the periphery of the ring-shaped unit, and that is housed inside the outer cylinder section; 
 an insulator that includes a ring-shaped insulating portion covering the ring-shaped unit, and a plurality of teeth insulating portions respectively covering the plurality of teeth; 
 a plurality of winding coil portions wound around the teeth and over the teeth insulating portions; 
 a centerpiece that includes a main body section disposed facing an opening of the outer cylinder section, and that supports the motor shaft and the stator core; 
 a first water stopping wall that is formed in a ring shape along the circumferential direction of the motor shaft, and that extends along an axial direction of the motor shaft from the ring-shaped insulating portion toward the main body section; 
 a second water stopping wall that is formed in a ring shape along the circumferential direction of the motor shaft, that extends out along the axial direction of the motor shaft from the main body section toward the ring-shaped insulating portion, and that, together with the first water stopping wall, configures a labyrinth structure positioned at a radial direction inside of the plurality of winding coil portions; 
 a third water stopping wall that is formed in a ring shape along the circumferential direction of the motor shaft, and that extends out along the axial direction of the motor shaft from the ring-shaped insulating portion toward the main body section; and 
 a fourth water stopping wall that is formed in a ring shape along the circumferential direction of the motor shaft, and that extends out along the axial direction of the motor shaft from the main body section toward the ring-shaped insulating portion, wherein: 
 the first water stopping wall and the second water stopping wall configure an inner labyrinth structure as the labyrinth structure, 
 the third water stopping wall and the fourth water stopping wall configure an outer labyrinth structure positioned at the radial direction inside of the plurality of winding coil portions and at a radial direction outside of the inner labyrinth structure, and 
 portions of the rotor housing run substantially parallel to the center piece, and the inner labyrinth structure and the outer labyrinth structure are each disposed closer to the center piece than to the portions of the rotor housing that run substantially parallel to the center piece. 
 
     
     
       2. The brushless motor of  claim 1 , wherein:
 the leading end side of the first water stopping wall overlaps along the axial direction of the motor shaft with the leading end side of the second water stopping wall; and 
 the leading end side of the third water stopping wall overlaps along the axial direction of the motor shaft with the leading end side of the fourth water stopping wall. 
 
     
     
       3. The brushless motor of  claim 1 , wherein the first water stopping wall is disposed at a radial direction inside of the second water stopping wall. 
     
     
       4. The brushless motor of  claim 3 , wherein:
 an extending portion is formed at the ring-shaped insulating portion so as to extend out toward a radial direction outside of the first water stopping wall; and 
 a leading end portion of the second water stopping wall faces the extending portion along the axial direction of the motor shaft. 
 
     
     
       5. The brushless motor of  claim 4 , wherein a radial direction outside end portion of the extending portion projects out further to a radial direction outside of the extending portion than the leading end portion of the second water stopping wall.